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2 Kudos
JB

New option for number of samples per channel

Status: New Submitted by Trusted Enthusiast on 03-09-2011 08:35 AM 4 Comment

Screenshot from the help for number of samples per channel for a Read task :

 

Extract of help.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Please add an option for a continuous sample task to read all currently available samples (-1) but with a wait for a minimum number of samples (#min). Behavior of this configuration :

  • #available samples >= #min : read all available samples
  • #available samples < #min : wait until #min samples are available or until timeout

 

This would be very useful in several cases. For example :

  • No extra coding to handle or avoid the error that appears if 0 sample is available.
  • Avoid the use of a wait function in the loop to ensure a minimum number of samples are available.
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3 Kudos
Mister_Rose

Axis formatting option in MAX

Status: New Submitted by Member on 11-01-2010 12:56 PM Comment

In MAX, you can open up a test panel for a DAQmx device.

 

I woudl like to format the numbers on the axis of the graphs. I have a calibration routine that requires that the signal get as close to 5 V as possible. When you get to less than 10mV, you the numbers on the vertical axis go from 5.01 to 5. So all you see on the graph is a bunch of 5's. It would be nice to be able to see the values in as much resolution as the channel will handle. Even at the maximum range, it can still do 2mV per bit. It would be nice to see 5.004 instead of 5.

 

 

 

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0 Kudos
jwdz

NI USB-443x _5 channels with software-selectable IEPE signal conditioning (0 or 2.1 mA)

Status: New Submitted by Active Participant on 10-16-2010 08:32 AM Comment

NI USB-4432 has 5 input，But only There are 4 channels with software-selectable IEPE signal conditioning (0 or 2.1 mA).

 

 

Make NI USB-4433  5 channels with software-selectable IEPE signal conditioning (0 or 2.1 mA).

 


 


 

3 Kudos
TCPlomp

DAQmx: Allow stacking of multiple scales

Status: New Submitted by Trusted Enthusiast on 10-09-2010 03:02 AM Comment

We normally have a DAQ system consisting of several elements:

-Sensor

-Custom filtering/attenuation

-Signal conditioning

-NI-DAQ device

 

When we use scales in DAQmx we have to create a scale for every 'route' we use (sometimes we have to use a 4 kAmps sensor for a 100 amps signal).

If we could define a scale in a task consisting of multiple scales, we could directly pick the sensor and signal conditioning we use for each signal. A change in one of these elements could easily be adjusted.

 

Ton

7 Kudos
jhfrontz

Post the NI-DAQmx base C Function Reference Help pages on your fora somewhere

Status: New Submitted by Member on 09-22-2010 07:16 PM 8 Comment

I continually come to your site looking for the DAQmx base API manual and have yet to find it.  I eventually have to dig out an old CD to find my copy.

 

How 'bout posting these online so that we can help ourselves out of jams?

 

Thanks,

Jeff

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1 Kudos
lukko

Software lossy and lossless compression in DAQmx.

Status: New Submitted by Member on 09-01-2010 08:53 AM Comment

Right now lossy and lossless compression can be achieved as presented here: Data Compaction for High-Speed Streaming to Disk where AI.RawDataCompressionType and AI.LossyLSBRemoval.CompressedSampleSize are used (see figure below).

lossy and lossless compression

In this case raw data are stored and additional header info has to be added. The idea is to implement and optimize it in DAQmx (DAQmx Configure Logging VI). This will allow high-speed streaming and to save disk space for higher sampling rates or long-term measurements.

 

Afterward implementation in the TDMS API could help to read directly compressed raw data without additional operations in LV. This will allow to work on TDMS files in Excel or Matlab using nilibdds.dll.

 

The issue is discussed a little here: Why the TDMS file is larger than it should be.

 

What do you think about it?

 

Lukasz Kocewiak

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5 Kudos
AndrewMc

Ability to split between multiple TDMS files while logging

Status: Implemented Submitted by on 07-12-2010 06:07 PM 10 Comment

It has come up a few times from customers, and I wanted to gauge interest and solicit ideas on how this should work.

 

Currently, with the built-in TDMS logging support, if you want to change to a new file in the middle of logging, you need to stop the task and start again.  For some use cases, this isn't practical (for example, http://forums.ni.com/t5/LabVIEW/Why-the-TDMS-file-is-larger-than-it-should-be/m-p/1176139#M511099).

 

The question is: How would you like to specify the "new file" behavior and what are your use cases?

 

For instance, a couple ideas to get the ball rolling:

  1. Add an interval attribute like "Change file after n samples".   We would then auto-increment the file name and change to that file when we have logged "n" samples.
  2. Make file path attribute changeable at runtime.  We have a file path attribute for logging.  The idea here would be to support changing the file path "on the fly" without stopping and starting the task.  The problem here is that it would not suit very well a use case where you want a specific file size.  Additionally, it wouldn't be as easy to use as #1; it would be more flexible though.
  3. (Any additional ideas/use cases?)

Thank you for your input!

 

Andy McRorie

NI R&D

It has come up a few times from customers, and I wanted to gauge interest and solicit ideas on how this should work.

 

Currently, with the built-in TDMS logging support, if you want to change to a new file in the middle of logging, you need to stop the task and start again.  For some use cases, this isn't practical (for example, http://forums.ni.com/t5/LabVIEW/Why-the-TDMS-file-is-larger-than-it-should-be/m-p/1176139#M511099).

 

The question is: How would you like to specify the "new file" behavior and what are your use cases?

 

What I'm currently thinking (because it seems the most flexible to different criteria and situations) is to simply allow you to set the file path property while the task is running (on DAQmx Read property node).  The only downside I can think of with this approach is that you wouldn't know exactly when we change to the new file.  We could guarantee within (for example) 1 second, but you wouldn't be able to specify the exact size.

 

Would this be a good solution for you?  Can you think of a better way to specify this behavior?

 

181 Kudos
manu.NET

Interactive DaqMx simulation interface ... (Popup panels for simulated hardware) ... Or better, DaqMx Simulation API for process simulation ...

Status: New Submitted by Active Participant on 03-31-2010 10:37 AM 18 Comment

Hello,

 

How often you have build Labview applications using simulated DaqMx boards ...

And how often you were limited by the default behaviour of simulated boards ... ( Sinewave for analogic inputs, Counter square signal for digital inputs ... )

 

It would be nice to integrate in DaqMx simulated boards, the abilty to modify the default behaviour of simulated inputs ... thru dedicated popups

 

It would be nice, for each task linked to a simulated daqMx board, to launch a popup window ...

 

  • For digital input, give the abilty to modify for each configured channel , the current binary value.
  • For analog input, give the ability to choose between a fixed value, a sine wave, a square signal ... white noise ...
  • For digital output, give the ability to view the current setted values
  • For analog output, give the ability to view the current simulated output value on a waveform chart ...

 

A more powerfull tool could also integrate a simulated channels switching mechanism ... A simulated output could be linked to a simulated input 

 

This feature could be a good way to create an application which could simulate a complete process ... this application could be used to validate a complete system

(such a kind of SIL architecture)

 

Other idea .... A complete daqMx simulation API ...

 

  • Creation of an API which could instanciate a simulated daqMx board (Wich could be seen via MAX)
    • Takes place of the actual limited daqMx simulated board
  • This device could then be accessed by other application thru daqMx
  • This API could have access to all channels of this simulated device.
  • This API could force, programmatically, the value of the simulated input channels according to a realistic process model

 

Something like this ...

 

 

 DaqMxSimulatedAPI.PNG

 

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